An importer recently found a dirty pallet covered in snails among their cargo from the UK… they called Biosecurity to check it out.
On closer inspection Biosecurity found more than just some snails lurking on the pallet; two species of non-native spider, seven snails, a European earwig and lots of soil and leaves were also stuck to it, or hiding in nooks and crannies. Most excitingly was a False Widow spider and her cocoon of baby spiders. By the time they had reached the Falklands the little spiders inside were fully developed and ready to hatch!
The hatchlings were filmed emerging from their egg sac over the coming days, in all about 50 perfectly formed baby spiders emerged.
False Widow spiders (Steatoda sp.) and are subject to much bad press in the UK as they have been known on occasion to bite people. Bites are extremely rare and although painful are not usually dangerous to humans.
False Widows lay hundreds of eggs in a special silk sac which keeps them safe until they are ready to hatch. Once emerged the spiderlings use fine strands of silk to catch a ride on air currents allowing them to travel vast distances. Although well adapted for dispersal they would never have been able to reach the Falklands without their second adaptation – their relationship with mankind. Among the False widows are the Cupboard spiders – the small shiny black spiders which are often found in cupboards or garden sheds. These species thrive in close proximity to humans as we provide them with the perfect habitat and help them spread around the world in cargo, on ships, planes and vehicles.
Three species of False Widow have been recorded in the Falklands and at least one species is established here. All of them have been introduced from overseas. We don’t know what effect, if any, they have on our native spiders or other invertebrates but it is important that we do all we can to stop alien species arriving in the Falklands. Thanks to a vigilant importer, this False Widow and her babies had a false start in the Falklands.